Lithophytes are

plants Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...

that grow in or on

rocks In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's ...

. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are also referred to as chasmophytes). Lithophytes can also be classified as being either obligate or facultative. Obligate lithophytes grow solely on rocks, while facultative lithophytes will grow partially on a rock and on another substrate simultaneously.

Nutrients

Lithophytes that grow on land feed off nutrients from rain water and nearby decaying plants, including their own dead tissue. It is easier for chasmophytes to acquire nutrients because they grow in fissures in rocks where soil or organic matter has accumulated. For most lithophytes,

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

is only available through interactions with the atmosphere. The most readily available form of nitrogen in the atmosphere is the gaseous state of

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

(NH₃). Lithophytes consume atmospheric ammonia through a concentration gradient that allows the compound to traverse the plants'

apoplast The ''apoplast '' is the extracellular space outside of plant cell membranes, especially the fluid-filled cell walls of adjacent cells where water and dissolved material can flow and diffuse freely. Fluid and material flows occurring in any extr ...

. Once free in the apoplast, gaseous ammonia is absorbed into metabolic cells by the enzyme

glutamine synthetase Glutamine synthetase (GS) () is an enzyme that catalyzes the condensation of glutamate and ammonia to form glutamine: Glutamate + ATP + NH3 → Glutamine + ADP + phosphate Glutamine synthetase uses ammonia produced by nitrate reduction ...

. To be able to absorb the few nutrients available on rocks or rocky substrates efficiently, lithophytes have evolved certain adaptations. They possess decreased numbers of root hairs and larger root diameters in comparison to other plant species. To add to this nutrient uptake efficiency, lithophytic plants have increased their relationship with arbuscular mycorrhizal fungi and dark septate endophyte fungi. These two types of fungi live inter- and intracellularly with the roots of lithophytes and a wide variety of other plant species. They increase the uptake of nutrients and water and have been found in greater concentrations in lithophytes.

Walls colonised as artificial cliffs by lithophytes

Asarina procumbens cascading down wall beside Paxton church gatepost

Walls, and other exposed stonework, are colonised by plants in a similar way to the colonisation of
cliff In geography and geology, a cliff or rock face is an area of Rock (geology), rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. ...
s and
scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. The term ''scree'' is ap ...
. These natural features are uncommon, especially in the lowlands, so walls are important for the conservation of plants which might otherwise be very isolated. Some wall plants even have 'wall' or 'muralis' as part of their common or scientific name such as wall-flower (''
Erysimum cheiri ''Erysimum cheiri'', syn. ''Cheiranthus cheiri'', the wallflower, is a species of flowering plant in the family Brassicaceae (Cruciferae), native to Greece, but widespread as an introduced species elsewhere. It is also treated as a hybrid under ...
'') or ivy-leaved toadflax ('' Cymbalaria muralis''), which shows their long established relationship with these man-made structures.

English Heritage English Heritage (officially the English Heritage Trust) is a charity that manages over 400 historic monuments, buildings and places. These include prehistoric sites, a battlefield, medieval castles, Roman forts, historic industrial sites, Lis ...

''Landscape Advice Note: Vegetation on Walls''

Examples

Examples of lithophytes include many

orchids Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Earth ...

such as ''

Dendrobium ''Dendrobium'' is a genus of mostly Epiphyte, epiphytic and Lithophyte, lithophytic orchids in the Family (biology), family Orchidaceae. It is a very large genus, containing more than 1,800 species that are found in diverse habitats throughout m ...

'' and ''

Paphiopedilum ''Paphiopedilum'', often called the Venus slipper, is a genus of the lady slipper orchid subfamily '' Cypripedioideae'' of the flowering plant family Orchidaceae. The genus comprises some 80 accepted taxa including several natural hybrids. The ...

'',

bromeliads The Bromeliaceae (the bromeliads) are a family of monocot flowering plants of about 80 genera and 3700 known species, native mainly to the tropical Americas, with several species found in the American subtropics and one in tropical west Africa, ...

such as ''

Tillandsia ''Tillandsia'' is a genus of around 650 species of evergreen, perennial plant, perennial flowering plants in the family (biology), family Bromeliaceae, native to the forests, mountains and deserts of the Neotropical realm, Neotropics, from northe ...

'', as well as many

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

and

liverwort Liverworts are a group of non-vascular land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry ...

s. Lithophytes have also been found in many other plant families, such as,

Liliaceae The lily family, Liliaceae, consists of about 15 genera and 610 species of flowering plants within the order Liliales. They are monocotyledonous, perennial, herbaceous, often bulbous geophytes. Plants in this family have evolved with a fai ...

Amaryllidaceae The Amaryllidaceae are a family of herbaceous, mainly perennial and bulbous (rarely rhizomatous) flowering plants in the monocot order Asparagales. The family takes its name from the genus '' Amaryllis'' and is commonly known as the amaryl ...

Begoniaceae Begoniaceae is a family of flowering plants with two genera and about 2040 species occurring in the subtropics and tropics of both the New World and Old World. All but one of the species are in the genus ''Begonia''. There have been many recent ...

Caprifoliaceae The Caprifoliaceae or honeysuckle family is a clade of dicotyledonous flowering plants consisting of about 860 species in 33 to 42 genera, with a nearly cosmopolitan distribution. Centres of diversity are found in eastern North America and easte ...

Crassulaceae The Crassulaceae (, from Latin ''crassus'', thick), also known as the crassulas, the stonecrops or the orpine family, are a diverse Family (biology), family of dicotyledon angiosperms primarily characterized by succulent leaves and a form of phot ...

Piperaceae The Piperaceae (), also known as the pepper family, are a large family (biology), family of flowering plants. The group contains roughly 3,600 currently accepted species in five genera. The vast majority of species can be found within the two mai ...

and

Selaginellaceae ''Selaginella'', also known as spikemosses or lesser clubmosses, is a genus of lycophyte. It is usually treated as the only genus in the family Selaginellaceae, with over 750 known species. This family is distinguished from Lycopodiaceae (the ...

Carnivorous plants

As nutrients tend to be rarely available to lithophytes or chasmophytes, many species of

carnivorous plants Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They have adapted to grow in waterlo ...

can be viewed as being

pre-adapted Exaptation or co-option is a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and be ...

to life on rocks. By consuming prey, these plants can gather more nutrients than non-carnivorous lithophytes.McPherson, S.R. (2010). ''Carnivorous Plants and their Habitats. Volume 1.'' Redfern Natural History Productions, Poole. pp. 176–180. Examples include the

pitcher plant Pitcher plants are carnivorous plants known as pitfall traps—a prey-trapping mechanism featuring a deep cavity filled with digestive liquid. The traps of pitcher plant are considered to be "true" pitcher plants and are formed by specialized ...

s ''

Nepenthes campanulata ''Nepenthes campanulata'' (; from Late Latin ''campānulātus'' "bell-shaped"), the bell-shaped pitcher-plant,Phillipps, A. & A. Lamb 1996. ''Pitcher-Plants of Borneo''. Natural History Publications (Borneo), Kota Kinabalu. is a tropical pitcher ...

'' and '' Heliamphora exappendiculata'', many ''

Pinguicula ''Pinguicula'', commonly known as butterworts, is a genus of carnivorous flowering plants in the family Lentibulariaceae. They use sticky, glandular leaves to lure, trap, and digest insects in order to supplement the poor mineral nutrition they ...

'' and several ''

Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, B ...

'' species.

Tennyson poem inspired by lithophyte

In the year 1863,

Alfred, Lord Tennyson Alfred Tennyson, 1st Baron Tennyson (; 6 August 1809 – 6 October 1892) was an English poet. He was the Poet Laureate during much of Queen Victoria's reign. In 1829, Tennyson was awarded the Chancellor's Gold Medal at Cambridge for one of ...

was moved to write his short and pithy poem of

metaphysical Metaphysics is the branch of philosophy that examines the basic structure of reality. It is traditionally seen as the study of mind-independent features of the world, but some theorists view it as an inquiry into the conceptual framework of h ...

speculation Flower in the Crannied Wall upon contemplating an unnamed lithophyte growing out of the masonry of the

wishing well A wishing well is a term from European folklore to describe water well, wells where it was thought that any spoken wish would be granted. The idea that a wish would be granted came from the notion that water housed deity, deities or had ...

at Waggoners Wells.

Flower in the crannied wall, I pluck you out of the crannies, I hold you here, root and all, in my hand, Little flower—but if I could understand What you are, root and all, and all in all, I should know what God and man is.''Poems of Alfred Lord Tennyson.'' Eugene Parsons (Introduction). New York: Thomas Y. Crowell Company, 1900.

Gallery

File:Erinus alpinus plant in flower.jpg, '' Erinus alpinus'', the fairy foxglove, growing out of a crack in the mortar of a stone wall File:Lithophytes at Chatswood West.jpg, Rock Felt Fern, Elkhorn fern, Birds Nest Fern and

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

growing on

Hawkesbury Sandstone Sydney sandstone, also known as the Hawkesbury sandstone, yellowblock, and yellow gold, is a sedimentary rock named after Sydney, and the Hawkesbury River north of Sydney, where this sandstone is particularly common. It forms the bedrock f ...

Chatswood West Chatswood West is a suburb on the Lower North Shore (Sydney), Lower North Shore of Sydney, in the state of New South Wales, Australia. Chatswood West is located 11 kilometres north-west of the Sydney central business district, in the Local gover ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

References

{{reflist Plant morphology Ecology terminology Plant life-forms Plants by habit Lithophytes he:מורפולוגיה של הצמח - מונחים#צורות חיים ושלבי חיים של צמחים